Structural and Molecular Interactions of CCR5 Inhibitors with CCR5

Kenji Maeda,Debananda Das,Hiromi Ogata-Aoki,Hirotomo Nakata,Toshikazu Miyakawa,Yasushi Tojo,Rachael Norman,Yoshikazu Takaoka,Jianping Ding,Gail F Arnold,Eddy Arnold,Hiroaki Mitsuya

doi:10.1074/jbc.m512688200

Abstract

We have characterized the structural and molecular interactions of CC-chemokine receptor 5 (CCR5) with three CCR5 inhibitors active against R5 human immunodeficiency virus type 1 (HIV-1) including the potent in vitro and in vivo CCR5 inhibitor aplaviroc (AVC). The data obtained with saturation binding assays and structural analyses delineated the key interactions responsible for the binding of CCR5 inhibitors with CCR5 and illustrated that their binding site is located in a predominantly lipophilic pocket in the interface of extracellular loops and within the upper transmembrane (TM) domain of CCR5. Mutations in the CCR5 binding sites of AVC decreased gp120 binding to CCR5 and the susceptibility to HIV-1 infection, although mutations in TM4 and TM5 that also decreased gp120 binding and HIV-1 infectivity had less effects on the binding of CC-chemokines, suggesting that CCR5 inhibition targeting appropriate regions might render the inhibition highly HIV-1-specific while preserving the CC chemokine-CCR5 interactions. The present data delineating residue by residue interactions of CCR5 with CCR5 inhibitors should not only help design more potent and more HIV-1-specific CCR5 inhibitors, but also give new insights into the dynamics of CC-chemokine-CCR5 interactions and the mechanisms of CCR5 involvement in the process of cellular entry of HIV-1.

Highlights

Active antiretroviral therapy has brought about a major impact on the acquired immunodeficiency syndrome (AIDS) epidemics in industrially advanced nations [1, 2], eradication of HIV-12 appears to be currently impossible mainly because of the viral reservoirs remaining in blood and infected tissues [3]
Site-directed Mutagenesis of chemokine receptor 5 (CCR5) and Binding Affinity of CCR5 Inhibitors—We have previously reported [11] that AVC competitively blocked the binding of a monoclonal antibody, 45531, which is known to be specific against the C-terminal half of the second extracellular loop (ECL2B) of CCR5 [21], whereas AVC failed to block or only partially blocked the binding of two other monoclonal antibodies, 2D7 and 45523, specific for CCR5 but not for its ECL2B
In an attempt to delineate the CCR5 binding profile of the three CCR5 inhibitors, we generated a variety of CCR5 mutant-overexpressing (CCR5MT) Chinese hamster ovary (CHO) cells and determined the KD values of each inhibitor to mutant CCR5 species using the saturation binding assay with tritiated inhibitors

Summary

Introduction

Active antiretroviral therapy has brought about a major impact on the acquired immunodeficiency syndrome (AIDS) epidemics in industrially advanced nations [1, 2], eradication of HIV-12 appears to be currently impossible mainly because of the viral reservoirs remaining in blood and infected tissues [3]. It was found that G163R exerts minimal effects on the binding of either SCH-C or TAK-779 to CCR5 (Table 1), potentially because these two inhibitors do not have direct hydrogen bond interactions with the ECL or ECL-TM interface.

Results

Conclusion